There are a few contrary voices in support of the Glazers' record, so the tedious argument does have to be joined with the fact that United have continued to be successful under their rule, winning four Premier League titles since 2005 and one Champions League, in 2008. The three most straightforward answers to that are: United, who were hugely rich, had no debt, a great manager and squad of top players when the Glazers arrived, might have been even more successful, perhaps dominated in Europe as well as the Premier League, had ?500m dead money not gone to bankers since.
Secondly, it is arguable that the Glazers' shrewdest move has been effectively to leave Old Trafford well alone, knowing that in Sir Alex Ferguson and David Gill, they had the partnership to maintain success, even given so much less money to play with.
Third, give the Glazers as much credit as you like, decide the playing success really is somehow all due to their absentee and debt-laden ownership, yet still no argument can be advanced for how leaking half a billion pounds out of the club, still to barely chip into the originally imposed debt, has been good for United.